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Can anyone help me identify this component? It just says 0 or D on it (I think it's a zero). I tested it for conductivity with a multimeter - doesn't seem to have any (tried both polarities in case it's a diode). Tested for resistance: nothing (i.e. infinite resistance), although I'm not 100% sure I was touching the contact points correctly, so don't take this as an ultimate measurement. Thanks in advance! enter image description here

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    \$\begingroup\$ That's a 0Ω resistor, a brigde in form of a chip resistor, so it can be easily placed by a machine. \$\endgroup\$ – Janka Jan 20 '19 at 14:12
  • \$\begingroup\$ Thanks. Well, I unsoldered it from the board and tried to test its conductivity, but there is none. I guess I could have damaged it during removal... \$\endgroup\$ – Todor K. Jan 20 '19 at 14:25
  • \$\begingroup\$ Zero ohm resistors are typically just there to connect point A to point B. Our manufacturers sometimes have these. Sometimes it's there to force voltage to enable something on the circuit, usually for testing. \$\endgroup\$ – KingDuken Jan 20 '19 at 17:38
  • \$\begingroup\$ I would bet money that that is a zero ohm resistor. You didn't damage it. You just aren't getting a good reading of the resistance for some reason. I have never seen one go open-circuit. \$\endgroup\$ – mkeith Jan 21 '19 at 10:22
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    \$\begingroup\$ Just a note on 0 ohm resistors; they are guaranteed to be less than 50 milliohms (for the vast majority of cases) so don't try bypassing a low resistance (current sense for example) with one as you may not achieve the aim. \$\endgroup\$ – Peter Smith Jan 21 '19 at 10:32
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This is a 0 Ohm resistor. Probably in 0805 package.

If the multimeter shows infinity (open circuit), or any significant resistance > 0, when measuring the element's resistance it means that it is damaged. The multimeter should show zero resistance when measuring such "resistor".

On the PCB you can replace it with a solder blob or a piece of wire.

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  • \$\begingroup\$ Can you clarify your second sentence? Why can an open circuit be replaced with a wire? \$\endgroup\$ – Pedro A Jan 20 '19 at 17:50
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    \$\begingroup\$ It wasn't intended to be an open circuit. The connection was intended to be shorted. This is the reason for the second sentence. \$\endgroup\$ – Metric Jan 20 '19 at 18:14
  • \$\begingroup\$ A lot of multimeters would not show zero Ohms but some value below 1 Ohm or below 100 milliohm. \$\endgroup\$ – Uwe Jan 21 '19 at 10:23
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That is an 0 Ohm Resistance. they also called SMD jumper resistors.

They are used as wire links to connect the traces on Surface mount boards, which can be assembled using pick and place machines easily. (same like jumper wires in through holes boards).

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It is an SMD resistor. As stated in the comments, the number indicates its resistance value; namely 0.

You mentioned you couldn't measure any resistance across it. Are you sure it's not coated?

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    \$\begingroup\$ Thanks. I removed it and tried testing for resistance/conductivity using its contact points on the underside, still the same result (no conductivity). But maybe those contact points or the "resistor" itself got damaged during removal. Anyway, it seems like everyone is pretty confident that it's a 0-ohm resistor and that's what I wanted to find out. I'll replace it with a jumper of some sort. Thanks! \$\endgroup\$ – Todor K. Jan 20 '19 at 14:31
  • \$\begingroup\$ On a side note: I have seen zero ohm resistors being used instead of a fuse, especially in IT hardware. I strongly advise not to replace it with a solder blob or a wire until you are sure the rest of the circuit is fine. Look out for a nearby voltage regulator. It may have shorted to protect the device from over-voltage. \$\endgroup\$ – Hermann Jan 20 '19 at 22:14
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    \$\begingroup\$ @Hermann I think you mean "opened" - it was already a short. Using an SMD resistor as a fuse would be like using a bolt instead of a fuse: they're not exactly designed to 'blow' like a fuse! The "use resistor instead of a fuse" is more to do with "fuses are expensive; resistors are cheap; this cheap circuit isn't worth protecting with a fuse; I'll just use a resistor". \$\endgroup\$ – John Burger Jan 20 '19 at 23:31
  • \$\begingroup\$ @TodorK. If you are able to, can you tell us the purpose of the board? \$\endgroup\$ – Metric Jan 21 '19 at 4:29
  • \$\begingroup\$ @JohnBurger The resistor opened, but the voltage regulator may have shorted. Indeed, it feels like a bold move, but have a look at a a discussion regarding a real-world example here. More to see here and to read here. \$\endgroup\$ – Hermann Jan 21 '19 at 8:55
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Be careful using a solder blob or too heavy a gauge of wire you might blow other components in the circuit. An analogy: Your car has blown a 5A fuse and your radio stops working, well you check and you don't have any 5A fuses on hand. So.... you substitute a 10A fuse instead, you could cause damage to the radio or whatever shares that circuit because too much current flowing through the 10A fuse. Better check to see if deices in that circuit could have caused to infinity reading in the 0 ohm resistor.

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  • \$\begingroup\$ A 0-ohm resistor should absolutely, never be used as a fuse. The traces that lead to the resistor probably have a current rating far lower than that resistor, anyhow. \$\endgroup\$ – sleblanc Jan 21 '19 at 15:55

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